Wireless communication device and wireless communication method

ABSTRACT

A wireless communication device serving as an NG60 WiGig device includes a PPDU generator that generates an MF control PHY PPDU (physical layer protocol data unit) including a legacy preamble, a legacy header, an NG60 header (a non-legacy header), a data field, and identification information indicating that the non-legacy header is included in the PPDU and a transmitter that transmits the generated MF control PHY PPDU.

BACKGROUND 1. Technical Field

The present disclosure relates to a wireless communication device and awireless communication method for generating and transmitting a physicallayer protocol data unit (PPDU).

2. Description of the Related Art

Wireless communication using the 60-GHz millimeter wave band(hereinafter referred to as “millimeter wave band communication”) hasdrawn attention because, for example, it is license-free. WiGig(Wireless Gigabit) is one of the standards for such millimeter wave bandcommunication and is a wireless communication standard ratified by theIEEE (Institute of Electrical and Electronics Engineers) as the IEEE802.11ad standard (refer to IEEE 802.11ad-2012).

The technology defined by WiGig (hereinafter referred to as “WiGigtechnology”) enables multi-gigabit high-speed digital transmission. Inaddition, the WiGig technology complements and extends the MAC (MediaAccess Control) layer of IEEE 802.11. Furthermore, WiGig technology hasdownward compatibility (also referred to as “backward compatibility”)with the IEEE 802.11 WLAN standard.

In addition, WiGig technology supports a centralized networkarchitecture, such as Infrastructure BSS (Basic Service Set) and PBSS(Personal BSS), in the MAC layer. Note that the term “centralizednetwork architecture” refers to a network structure in which a centralcoordinator, such as an access point (AP) or a personal BSS controlpoint (PCP), transmits a beacon to synchronize all of stations (STAs) ina network. In addition, WiGig technology achieves directionaltransmission by using BF (beam forming) more widely than other IEEE802.11 WLAN technologies operating in the 2.4-GHz or 5-GHz frequencyband.

As described above, WiGig has drawn attention because it has manyadvantages, such as high-speed communication, backward compatibility,support for a centralized network architecture and beamforming.

Common use of WiGig technology is to replace wired communicationperformed by using a cable in a wired digital interface with wirelesscommunication. For example, by employing WiGig technology, a wirelessUSB (Universal Serial Bus) link for instant synchronization and awireless HDMI (registered trademark) (High-Definition MultimediaInterface) link for video streaming can be provided between terminals,such as smartphones and tablets.

SUMMARY

However, the most recent wired digital interfaces, such as USB 3.5 orHDMI (registered trademark) 1.3, enable data transmission of up toseveral tens of Gbps. Therefore, further evolution of WiGig technologyis required so as to provide a data transmission rate comparable to themost recent wired digital interface in wireless communication.

One non-limiting and exemplary embodiment provides a wirelesscommunication device and a wireless communication method capable offurther increasing the data transmission rate in WiGig technology whilemaintaining backward compatibility with the IEEE 802.11 WLAN standard.

In one general aspect, the techniques disclosed here feature a wirelesscommunication device including a physical layer protocol data unit(PPDU) generator that generates a PPDU including a legacy preamble, alegacy header, a non-legacy header, a data field, and identificationinformation indicating that the non-legacy header is included in thePPDU and a transmitter that transmits the PPDU.

According to the present disclosure, the wireless communication devicecan facilitate increasing the data transmission rate while maintainingbackward compatibility with the IEEE 802.11 WLAN standard.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an LF control PHY PPDU format, which isthe underlying technology used by the present disclosure;

FIG. 2 illustrates an example of the structure of a legacy header, whichis the underlying technology used by the present disclosure;

FIG. 3 is a block diagram illustrating an example of the configurationof a transmission baseband processor of a legacy WiGig device, which isthe underlying technology used by the present disclosure;

FIG. 4 illustrates an example of the structure of a header LDPCcodeword, which is the underlying technology used by the presentdisclosure;

FIG. 5 is a block diagram illustrating an example of the configurationof a wireless communication device (an NG60 WiGig device) according to afirst embodiment;

FIG. 6 illustrates an example of the format of an MF control PHY PPDUaccording to the first embodiment;

FIG. 7 illustrates an example of the structure of an NG60 headeraccording to the first embodiment;

FIG. 8 is a block diagram illustrating an example of the configurationof a transmission baseband processor according to the first embodiment;

FIG. 9 illustrates an example of the structure of a legacy header LDPCcodeword according to the first embodiment;

FIG. 10 illustrates an example of the structure of an NG60 header LDPCcodeword according to the first embodiment;

FIG. 11 is a block diagram illustrating an example of the configurationof a reception baseband processor according to the first embodiment;

FIG. 12 illustrates another example of a method for transmitting an MFcontrol PHY PPDU according to the first embodiment;

FIG. 13 is a block diagram illustrating an example of the configurationof an NG60 WiGig device according to a second embodiment;

FIG. 14 illustrates an example of the format of an MF control PHY PPDUaccording to the second embodiment;

FIG. 15 illustrates an example of the structure of an NG60 headeraccording to the second embodiment;

FIG. 16 illustrates another example of the structure of the NG60 headeraccording to the second embodiment;

FIG. 17 illustrates an example of the structure of a header LDPCcodeword according to the second embodiment; and

FIG. 18 illustrates another example of the method for transmitting an MFcontrol PHY PPDU according to the second embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described in detail below withreference to the accompanying drawings.

The outline of the existing WiGig technology described in IEEE802.11ad-2012, which is the underlying technology on which theembodiments of the present disclosure are based, is described first. Toclarify the difference between the existing WiGig technology and theWiGig technology according to the present disclosure, the word “legacy”is attached to terms related to the existing WiGig technology as needed.

Overview of Legacy WiGig

Legacy WiGig technology can provide a PHY (physical layer) data rate ofup to 6.7 Gbps by using a standard bandwidth of 2.16 GHz. In the legacyWiGig, the physical layer supports three modulation schemes: controlmodulation, single carrier (SC) modulation, and OFDM (OrthogonalFrequency Division Multiplexing) modulation. Physical layers modulatedby using these modulation schemes are called “control PHY”, “SC PHY”,and “OFDM PHY”, respectively.

The control PHY is mainly used to transmit a control/extension framerelated to beamforming (BF) training. Examples of a control/extensionframe include a sector sweep (SSW) frame, an SSW feedback frame, a beamrefinement protocol (BRP) frame, and a directional multi-gigabit (DMG)beacon frame.

In addition, the control PHY is used to transmit a control frame relatedto collision avoidance. Examples of a control frame include an RTS(Request-to-Send) frame, a DMG CTS (Clear-to-Send: transmission allowed)frame, and a DMG DTS (Denial-to-Send: transmission denied) frame.

Unlike the SC PHY and OFDM PHY, control PHY uses a single modulation andcoding scheme (MCS) with a very low PHY data rate of about 27.5 Mbps. Asa result, the control PHY of the legacy WiGig technology can supportwireless transmission much more robustly than SC PHY and OFDM PHY.

Control PHY PPDU Format

The format of the physical layer frame in the legacy WiGig is describedbelow. Note that in the following description, the physical layer framein the legacy WiGig is referred to as “LF control PHY PPDU”. Here, theterm “LF” refers to a legacy format, and the term “PPDU” refers to aphysical layer protocol data Unit.

FIG. 1 illustrates an example of the format of an LF control PHY PPDU.

As illustrated in FIG. 1, an LF control PHY PPDU 10 includes a legacypreamble 11, a legacy header 12, and a data field 13 in this order. Whenused for the purpose of beam refinement, the LF control PHY PPDU 10further optionally includes an AGC (automatic gain control) subfield 14and a TRN-R/T subfield 15 subsequent to the data field 13.

The legacy preamble 11 has information for identifying the LF controlPHY PPDU 10 set forth therein. The legacy preamble 11 includes STF(short training field) 16 and CEF (channel estimation field) 17.

STF 16 is a field used for packet detection, automatic gain control(AGC), frequency offset estimation, synchronization, and frame typeindication. STF 16 is built using 50 predefined Golay sequences Ga128and Gb128. The length of each of the Golay sequences Ga and Gb is 128.

For example, the waveform of the STF 16 is given by the followingexpression (1):

$\begin{matrix}{{r_{STF}\left( {nT}_{c} \right)} = \left\{ \begin{matrix}\begin{matrix}{{{{Gb}_{128}\left( {n\; {{mod}128}} \right)}{\exp \left( {j\; \pi \frac{n}{2}} \right)}},} \\{{n = 0},1,\ldots \mspace{14mu},{{48 \times 128} - 1}}\end{matrix} \\\begin{matrix}{{{- {{Gb}_{128}\left( {n\; {mod}\; 128} \right)}}{\exp \left( {j\; \pi \frac{n}{2}} \right)}},} \\{{n = {48 \times 128}},\ldots \mspace{14mu},{{49 \times 128} - 1}}\end{matrix} \\\begin{matrix}{{{- {{Ga}_{128}\left( {n\; {{mod}128}} \right)}}{\exp \left( {j\; \pi \frac{n}{2}} \right)}},} \\{{n = {49 \times 128}},\ldots \mspace{14mu},{{50 \times 128} - 1}}\end{matrix}\end{matrix} \right.} & (1)\end{matrix}$

In expression (1), Tc is the SC chip time, which is 0.57 nanoseconds.“mod” represents a modulus operation. The Golay sequences Ga128(n) andGb128(n) are defined in the range of 0≦n≦127. For n outside this range,the Golay sequences Ga128(n) and Gb128(n) are set to 0.

CEF 17 is a field used for channel estimation. CEF 17 is built usingnine Golay sequences each having a length of 128.

For example, the waveform of the CEF 17 is given by the followingexpression (2):

$\begin{matrix}{{{r_{CE}\left( {nT}_{c} \right)} = {\left( {{{Gu}_{512}(n)} + {{Gv}_{512}\left( {n - 512} \right)} + {{Gv}_{512}\left( {n - 1024} \right)}} \right){\exp \left( {j\; \pi \frac{n}{2}} \right)}}},{n = 0},1,\ldots \mspace{14mu},1151} & (2)\end{matrix}$

In expression (2), Gu₅₁₂ and Gv₅₁₂ are defined by, for example, thefollowing expressions (3):

Gu ₅₁₂ =[−Gb ₁₂₈ −Ga ₁₂₈ Gb ₁₂₈ −Ga ₁₂₈]

Gv ₅₁₂ =[−Gb ₁₂₈ Ga ₁₂₈ −Gb ₁₂₈ −Ga ₁₂₈]  (3)

The legacy header 12 includes a plurality of fields and has varioustypes of pieces of information about the details of the LF control PHYPPDU 10 set forth therein. The structure of the legacy header 12 isdescribed in more detail below.

The data field 13 consists of payload data of a PHY service data unit(hereinafter referred to as “PSDU”).

The AGC subfield 14 and the TRN-R/T subfield 15 has information aboutbeam refinement set forth therein.

FIG. 2 illustrates an example of the structure of the legacy header 12.

As illustrated in FIG. 2, the legacy header 12 includes a reservedfield, a scrambler initialization field, a length field, a packet typefield, a training length field, a turnaround field, a reserved bitfield, and a header check sequence (HCS) field. The bit width anddescription of each of the fields are illustrated in FIG. 2.

For example, the length field of the legacy header 12 specifies thenumber of data octets in the PSDU. The training length field of thelegacy header 12 specifies the length of the AGC subfield 14 and theTRN-R/T subfield 15. The packet type field of the legacy header 12specifies which one of the TRN-R field and the TRN-T field exists in theTRN-R/T subfield 15.

A wireless communication device supporting the legacy WiGig (hereinafterreferred to as “legacy WiGig device”) adds a legacy preamble 11 and alegacy header 12 before the payload data of a PSDU to be transmitted andgenerates the LF control PHY PPDU 10 having the format illustrated inFIG. 1. Thereafter, the legacy WiGig device performs transmissionbaseband processing, such as scrambling, coding, modulation, andspreading, on the generated LF control PHY PPDU 10. Subsequently, thelegacy WiGig device outputs the generated LF control PHY PPDU 10 from aradio antenna.

Configuration of Legacy WiGig Device

FIG. 3 is a block diagram illustrating an example of the configurationof a transmission baseband processor (transmitter) of a legacy WiGigdevice.

In FIG. 3, a transmission baseband processor 20 of the legacy WiGigdevice includes a scrambler 21, an LDPC (low density parity check)encoder 22, a modulator 23, and a spreader 24.

The scrambler 21 scrambles the bits of the legacy header 12 and the datafield 13 of the LF control PHY PPDU 10 (refer to FIG. 1) in accordancewith a predefined scrambling rule.

A shift register of the scrambler 21 is initialized in accordance withthe scrambler initialization field (refer to FIG. 2) of the legacyheader 12. As a result, the scrambler 21 continues to scramble the bitsstarting from a bit of the length field of the legacy header 12 (a bitimmediately after the scrambler initialization field) to the end of thedata field 13 without resetting the shift register.

Thereafter, the scrambler 21 outputs, to the LDPC encoder 22, the LFcontrol PHY PPDU 10 having a portion of the legacy header 12 subsequentto the length field and a portion of the data field 13 that arescrambled.

The LDPC encoder 22 performs LDPC coding (error correction coding) onthe bits of the legacy header 12 and the bits of the data field 13 ofthe LF control PHY PPDU 10 output from the scrambler 21 with anapproximate code rate of 1/2. The LDPC coding is performed in accordancewith a predefined coding rule. As a result, the LDPC encoder 22generates a plurality of LDPC codewords. Thereafter, the LDPC encoder 22outputs, to the modulator 23, the LF control PHY PPDU 10 having theLDPC-coded portion of the legacy header 12 and the LDPC coded portion ofthe data field 13.

Note that in the following description, the first LDPC codeword, namely,the LDPC codeword including the bits of the legacy header 12 is referredto as a “header LDPC codeword”. In addition, the second LDPC codeword,namely, the LDPC codeword including the bits of the portion of the datafield 13 is referred to as a “data LDPC codeword”.

FIG. 4 illustrates an example of the structure of the header LDPCcodeword.

As illustrated in FIG. 4, a header LDPC codeword 30 is formed fromheader bits 31, data bits 32, and parity bits 33 arranged in this order.

The header bits 31 have a length of 5 octets and represent an LDPCcodeword of the legacy header 12. The data bits 32 have a length of 6octets and represent an LDPC codeword of a first portion of data field13. The parity bits 33 have a length of 21 octets and represent paritybits appended for error correction coding to be performed on the headerbits 31 and the data bits 32.

The modulator 23 modulates the above-described plurality of LDPCcodewords (the header LDPC codeword and the data LDPC codeword) includedin the LF control PHY PPDU 10 output from the LDPC encoder 22 by usingDBPSK (Differential Binary Phase Shift Keying). As a result, themodulator 23 converts each of the plurality of LDPC codewords into astream of complex constellation points. Thereafter, the modulator 23outputs, to the spreader 24, the LF control PHY PPDU 10 having themodulated portions of the legacy header 12 and the data field 13.

The spreader 24 spreads each of the constellation points included in thestream included in the LF control PHY PPDU 10 output from the modulator23 by using a predefined Golay sequence Ga32 having a length of 32.Thereafter, the spreader 24 outputs, to a radio antenna (notillustrated) provided in the legacy WiGig device, the LF control PHYPPDU 10 having the spread portions of the legacy header 12 and the datafield 13.

For example, the waveform of the diffused constellation point is givenby the following expression (4):

$\begin{matrix}{{{r_{{HEADER},{DATA}}\left( {nT}_{c} \right)} = {\left( {{{Ga}_{32}\left( {n\; {mod}\; 32} \right)} \cdot {d\left( \left\lfloor \frac{n}{32} \right\rfloor \right)}} \right){\exp \left( {j\; \pi \; \frac{\pi}{2}} \right)}}},{n = 0},1} & (4)\end{matrix}$

In expression (4), d(k) is defined by the following expressions (5):

d(k)=s(k)×d(k−1)

s(k)=2c _(k)−1   (5)

Note that s(0) is the first bit of the legacy header 12. d(−1) is set to1 when used in differential encoding. {c_(k), k=0, 1, 2, . . . } arecoded bits in a plurality of LDPC codewords.

The radio antenna of the legacy WiGig device (not illustrated in FIG. 3)wirelessly transmits the LF control PHY PPDU 10 output from the spreader24.

In this manner, the legacy WiGig device on the transmitting sideperforms transmission baseband processing including scrambling, LDPCcoding, modulation, and spreading on the portion from the legacy header12 to the data field 13 in the LF control PHY PPDU 10 and transmits theLF control PHY PPDU 10.

In addition, if the received signal includes the LF control PHY PPDU 10,the legacy WiGig device on the receiving side detects the legacypreamble 11 from the received signal and extracts the LF control PHYPPDU 10.

Subsequently, the legacy WiGig device on the receiving side performs acalculation process that is the reverse of the calculation processperformed by the legacy WiGig device on the transmitting side on theportion from the middle of the legacy header 12 to the data field 13 ofthe extracted LF control PHY PPDU 10. That is, the legacy WiGig deviceon the receiving side performs reception baseband processing includingdespreading, demodulation, LDPC decoding, and descrambling on theportion. In this manner, the legacy WiGig device restores the LF controlPHY PPDU 10 to obtain the original LF control PHY PPDU 10.

Subsequently, the legacy WiGig device on the receiving side extracts thebits of the data field 13 from the restored LF control PHY PPDU 10.

As described above, in the legacy WiGig technology, the control PHY PPDUto be transmitted and received in the physical layer is transmitted withthe portion from the legacy header 12 to the data field 13 encoded.Thereafter, by detecting the legacy preamble 11 and decoding the legacyheader 12, the data field 13 can be decoded and extracted.

Outline of Present Disclosure

The next-generation WiGig according to the present disclosure isdescribed below. The next-generation WiGig according to the presentdisclosure is a technology that increases the data transmission rate,compared with the legacy WiGig, while maintaining the backwardcompatibility with the IEEE 802.11 WLAN standard. To clarify thedifference from the existing WiGig technology, the term “NG60”(next-generation 60 GHz) is attached to terms related to the WiGigtechnology according to the present disclosure as needed.

The NG60 WiGig technology according to the present disclosure providesan increase in data transmission rate by supporting transmission thatmakes use of variable bandwidth.

In addition, backward compatibility with legacy WiGig (includingbackward compatibility with the IEEE 802.11 WLAN standard) is providedby using a format having the legacy preamble 11 and legacy header 12.

For this reason, the NG60 WiGig defines a mixed format (MF) PPDU inwhich a legacy format PPDU including the above-mentioned LF control PHYPPDU 10 is combined with a format corresponding to transmission usingvariable bandwidth. Note that the LF control PHY PPDU is transmittedover the standard bandwidth.

Like the legacy format PPDU, the mixed format PPDU can support threemodulation schemes: control modulation, single carrier modulation, andOFDM modulation. That is, the mixed format PPDU can have three types: MFcontrol PHY PPDU, MF SC PHY PPDU, and MF OFDM PHY PPDU.

According to the present disclosure, the format of the MF control PHYPPDU among the mixed format PPDUs of the NG60 WiGig and transmission andreception processing of the format are described. The MF control PHYPPDU of NG60 WiGig corresponds to the LF control PHY PPDU 10 (refer toFIG. 1) of the legacy WiGig.

In the MF control PHY PPDU, an NG60 header (a non-legacy header) havinginformation about transmission that makes use of variable bandwidth setforth therein and a data field are disposed in this order after thelegacy preamble 11 and the legacy header 12 illustrated in FIG. 1 (referto FIGS. 6 and 14). That is, the NG60 header and the data field aredisposed in a portion corresponding to the data field 13 of the LFcontrol PHY PPDU 10. That is, the MF control PHY PPDU includes the NG60header without changing the structure of the LF control PHY PPDU 10 ofthe legacy WiGig in which the legacy preamble 11 and the legacy header12 are disposed at the top.

In this manner, NG60 WiGig can maintain backward compatibility withlegacy WiGig. That is, a legacy WiGig device can decode the legacyportion (i.e., the legacy preamble 11 and the legacy header 12) evenwhen the legacy WiGig device receives an MF control PHY PPDU.

In addition, if the received control PHY PPDU includes the NG60 header,the NG60 WiGig device needs to detect and extract the NG60 header. Thatis, the NG60 WiGig device needs to distinguish the MF control PHY PPDUfrom the LF control PHY PPDU 10.

Therefore, in the NG60 WiGig, the MF control PHY PPDU includesidentification information indicating that the NG60 header is includedin the physical layer.

Such identification information can be provided by, for example,rotating the phase of the DBPSK modulation at the start position of theNG60 header or by setting predetermined format identificationinformation at a predetermined position of the PPDU.

The details of the NG60 WiGig device are described below for each of thecase where the identification information is provided in the NG60 headerby rotating the phase of the DBPSK modulation and the case where theidentification information is provided in the NG60 header by using theformat identification information set forth in the control PHY PPDU.

First Embodiment

As a first embodiment of the present disclosure, an NG60 WiGig deviceused in the case where the identification information is provided in theNG60 header by rotating the phase of the DBPSK modulation is describedfirst.

Configuration of Device

FIG. 5 is a block diagram illustrating an example of the configurationof the wireless communication device (the NG60 WiGig device) accordingto the present embodiment.

The wireless communication device according to the present embodimentincludes, for example, a CPU (Central Processing Unit), a storagemedium, such as a ROM (Read Only Memory), that stores a control program,a work memory, such as a RAM (Random Access Memory), and a communicationcircuit (none are illustrated). In this case, the function of each ofthe units of the wireless communication device is provided by, forexample, the CPU executing the control program.

In FIG. 5, a wireless communication device 100, which is an NG60 WiGigdevice according to the present embodiment, includes a controller 200, atransmission processor 300, an antenna unit 400 having a plurality ofradio antennas, and a reception processor 500.

The controller 200 performs various types of data processing of theupper layer, exchanges data between the physical layer and the upperlayer, and wirelessly transmits and receives data by using thetransmission processor 300, the antenna unit 400, and the receptionprocessor 500. The controller 100 includes a PPDU generator 210.

The PPDU generator 210 generates an MF control PHY PPDU from the payloaddata of the PSDU and transmits the generated MF control PHY PPDU byusing the transmission processor 300 and the antenna unit 400.

PPDU Format

The format of the control PHY PPDU in the NG60 WiGig, that is, theformat of the MF control PHY PPDU generated by the PPDU generator 210 isdescribed below.

FIG. 6 illustrates an example of the format of an MF control PHY PPDU.FIG. 6 corresponds to FIG. 1.

As illustrated in FIG. 6, an MF control PHY PPDU 600 has a legacypreamble 601, a legacy header 602, a first padding field 603, an NG60header 604, and a second padding field 605 arranged in this order. Inaddition, the MF control PHY PPDU 600 has an NG60 STF 606, a pluralityof NG60 CEFs 607, and a data field 608 arranged in this order subsequentto the second padding field 605.

Note that, when used for beam refinement, the MF control PHY PPDU 600may further has an AGC subfield 609 and a TRN-R/T subfield 610subsequent to the data field 608. That is, the AGC subfield 609 and theTRN-R/T subfield 610 are optional.

The legacy preamble 601 has a waveform the same as the waveform of thelegacy preamble 11 of the LF control PHY PPDU 10.

The legacy header 602 has the same configuration as the legacy header 12of the LF control PHY PPDU 10 (refer to FIG. 2).

The first padding field 603 and the second padding field 605 are areasthat are inserted to, for example, adjust the data length.

The NG60 header 604 provides information about the details of the MFcontrol PHY PPDU 600 by itself or together with the legacy header 602.The details of the structure of the NG60 header 604 are described below.

The NG60 STF 606 is an area used for retraining of automatic gaincontrol (AGC).

Since the NG60 STF 606 is used for such retraining and its function issimpler, the NG60 STF 606 can be made shorter than the STF 16 of LFcontrol PHY PPDU 10 (refer to FIG. 1).

For example, the NG60 STF 606 can be formed by using 25 Golay sequencesGb128 each having a length of 128. For example, the NG60 STF 606 has thewaveform given by the following expression (6):

$\begin{matrix}{{{r_{{NG}\; 6\; 0\; {STF}}\left( {nT}_{c} \right)} = {{G_{b\; 128}\left( {n\; {mod}\; 128} \right)}{\exp \left( {j\; \pi \mspace{11mu} \frac{\pi}{2}} \right)}}},{n = 0},1,\ldots \mspace{20mu},{{25 \times 128} - 1}} & (6)\end{matrix}$

A plurality of NG60 CEFs 607 are an area used for channel estimation ofa plurality of space-time streams generated for the data field 608 bythe transmission processor 300 in the subsequent stage. Each of theplurality of NG60 CEFs 607 can be formed in the same manner as thelegacy CEF 17 (refer to FIG. 1) of the LF control PHY PPDU 10. That is,the NG60 CEFs 607 can have a waveform given by the above-mentionedexpressions (2) and (3).

The number of NG60 CEFs 607 in one MF control PHY PPDU 600 is determinedby the number of space-time streams generated from the data field 608.

For example, the number (N) of the NG60 CEFs 607 (refer to FIG. 6) isgreater than or equal to the number of space-time streams generated fromthe data field 608. For example, when the number of space-time streamsis 2, the number of the NG60 CEFs 607 (refer to FIG. 6) can be set to 2.Alternatively, when the number of space-time streams is 3, the number ofthe NG60 CEFs 607 (refer to FIG. 6) can be set to 4.

The data field 608 stores the payload data of the PSDU. The data field608 is a data portion to be transmitted by using a plurality ofspace-time streams.

The AGC subfield 609 and the TRN-R/T subfield 610 has information aboutbeam refinement set forth therein.

That is, the PPDU generator 210 acquires the payload data of the PSDU tobe transmitted and sets the payload data as the data field 608.Thereafter, the PPDU generator 210 adds a portion from the legacypreamble 601 to the plurality of NG60 CEFs 607 before the data field 608so as to generate an MF control PHY PPDU 600.

FIG. 7 illustrates an example of the structure of the NG60 header 604.FIG. 7 corresponds to FIG. 2.

As illustrated in FIG. 7, the NG60 header 604 has a CBW (channelbandwidth information) field, a length field, an N_(sts) field, areserved bit field, and an HCS field. The bit width and description ofeach of the fields are illustrated in FIG. 7.

For example, the CBW field of the NG60 header 604 specifies the channelbandwidth. The length field of the NG60 header 604 specifies the numberof data octets in the PSDU. N_(sts) of the NG60 header 604 specifies thenumber of space-time streams generated from the data field 608.

Note that the PPDU generator 210 sets a value in the length field of thelegacy header 602 while taking into account the entire portion from thefirst padding field 603 to the data field 608. In this manner, uponreceiving the MF control PHY PPDU 600, the legacy WiGig device cancorrectly determine the number of data octets in the PSDU.

As used herein, the value in the length field of the legacy header 602is referred to as a legacy length field value L_(LH), and the value ofthe length field of the NG60 header 604 is referred to as an NG60 lengthfield value L_(NH).

The PPDU generator 210 calculates the sum of the NG60 length field valueL_(NH), the lengths of the first padding field 603, the NG60 header 604,and the second padding field 605 (i.e., 17 octets), and the equivalentlength of the NG60 STF 606 and the NG60 CEFs 607. Thereafter, the PPDUgenerator 210 sets the legacy length field value L_(LH) to thecalculated sum.

As described below, the transmission baseband processor 310 performsDBPSK modulation and LDPC coding with an approximate code rate of 1/2.Therefore, the equivalent length of NG60 STF 606 and NG60 CEFs 607 isequal to a value obtained by dividing the actual length of NG60 STF 606and NG60 CEFs 607 by 64, i.e., 6.25+N_(sts)×2.25 octets. Here, asdescribed above, N_(sts) is the number of space-time streams generatedfrom the data field 608.

Therefore, the legacy length field value L_(LH) is given by, forexample, the following expression (7):

L _(LH) =L _(NH)+23.25+N _(sts)×2.25   (7)

It is obvious that the legacy length field value L_(LH) is greater thanthe NG60 length field value L_(NH) at all times. In addition, asillustrated in FIG. 2, the legacy length field value L_(LH) is less thanor equal to 1023 octets. Accordingly, the following expression (8) isderived from expression (7):

N _(sts)×2.25≦999.75−L _(NH)   (8)

That is, the number N_(sts) of space-time streams generated from thedata field 608 depends on the NG60 length field value L_(NH). In otherwords, the space-time coding (STC) scheme used for transmission of thedata field 608 depends on the length of the data field 608.

Therefore, the PPDU generator 210 sets the NG60 length field valueL_(NH) and the legacy length field value L_(LH) so as to conform to thespace-time coding (STC) method (the number of space-time streamsN_(sts)) used to transmit the data field 608. That is, the PPDUgenerator 210 generates an MF control PHY PPDU 600 having the legacylength field value L_(LH) and the NG60 length field value L_(NH) thatsatisfy expressions (7) and (8).

Note that in the case of the MF control PHY PPDU 600, unless the NG60header 604 is properly decoded on the receiving side, the channelbandwidth information (CBW) cannot be detected and, therefore, it isdifficult to decode the space-time stream. Thus, although the NG60 STF606 to TRN-R/T subfield 610 can be transmitted using variable bandwidth,the legacy preamble 601 to the second padding field 605 need to betransmitted using the standard bandwidth.

Configuration of Transmission Processor

The transmission processor 300 illustrated in FIG. 5 performspredetermined transmission baseband processing on the MF control PHYPPDU 600 (refer to FIG. 6) output from the controller 200. Thereafter,the transmission processor 300 outputs the MF control PHY PPDU 600 tothe antenna unit 400. The transmission processor 300 includes atransmission baseband processor 310 and a transmission RF front end 320.

The transmission baseband processor 310 performs transmission basebandprocessing, such as scrambling, LDPC coding, DBPSK modulation,spreading, and space-time coding, on the MF control PHY PPDU 600.Thereafter, the transmission baseband processor 310 outputs, to thetransmission RF front end 320, the MF control PHY PPDU 600 subjected tothe transmission baseband processing.

Note that the transmission baseband processor 310 performs DBPSKmodulation on the LDPC codeword of the NG60 header 604 with 90-degreephase rotation, for example. That is, the transmission basebandprocessor 310 rotates the phase of the modulation signal of the portionof the NG60 header 604 by 90 degrees with respect to the phase of themodulation signal of the other portion. The amount of rotation of thephase is not limited to 90 degrees. For example, the amount of rotationmay be −90 degrees. Any other amount of rotation may be employed if thereceiving device can distinguish the constellation point of themodulation signal of the portion of the NG60 header 604 from theconstellation point of the modulation signal of the other portion.

Configuration of Transmission Baseband Processor

FIG. 8 is a block diagram illustrating an example of the configurationof the transmission baseband processor 310. FIG. 8 corresponds to FIG.3.

As illustrated in FIG. 8, the transmission baseband processor 310includes a scrambler 311, an LDPC encoder 312, a modulator 313, aspreader 314, and an STC encoder 315.

The scrambler 311 scrambles the bits of the legacy header 602, the firstpadding field 603, the NG60 header 604, the second padding field 605,and the data field 608 (refer to FIG. 6) of the MF control PHY PPDU 600output from the controller 200 in accordance with the same scramblingrule as the legacy WiGig.

The shift register of the scrambler 311 is initialized in accordancewith the scrambler initialization field (refer to FIG. 2) of the legacyheader 602. As a result, the scrambler 311 continuously scrambles aportion after the length field of the legacy header 602 (immediatelyafter the scrambler initialization field), a first padding field 603, anNG60 header 604, a second padding field 605, and a data field 608without resetting the shift register.

Thereafter, the scrambler 311 outputs, to the LDPC encoder 312, the MFcontrol PHY PPDU 600 having the portion of the legacy header 602 fromthe length field to the second padding field 605 and the portion of thedata field 608 that are scrambled.

The LDPC encoder 312 performs LDPC coding on the MF control PHY PPDU 600output from the scrambler 311 with an approximate code rate of 1/2 inaccordance with the same encoding rule as for the legacy WiGig togenerate a plurality of LDPC codewords. Thereafter, the LDPC encoder 312outputs, to the modulator 313, the MF control PHY PPDU 600 having theportion from the legacy header 602 to the second padding field 605 andthe portion of the data field 608 that are LDPC coded.

In the following description, the first LDPC codeword, that is, the LDPCcodeword including the bits of the legacy header 602, is referred to asa “legacy header LDPC codeword”. The second LDPC codeword, that is, theLDPC codeword including the bits of the NG60 header 604, is referred toas “NG60 header LDPC codeword”. Each of the third LDPC codewords and thesubsequent LDPC codewords, that is, an LDPC codeword that does notinclude the bits of the legacy header 602 and the bits of the NG60header 604, is referred to as a “data LDPC codeword”.

That is, the legacy header LDPC codeword and the NG60 header LDPCcodeword are generated in the same manner as the header LDPC codeword ofthe legacy WiGig technology. In addition, the data LDPC codeword isgenerated in the same manner as the data LDPC codeword of the legacyWiGig technology.

FIG. 9 illustrates an example of the structure of the legacy header LDPCcodeword. In addition, FIG. 10 illustrates an example of the structureof the NG60 header LDPC codeword. Each of FIGS. 9 and 10 corresponds toFIG. 4.

As illustrated in FIG. 9, the legacy header LDPC codeword 620 has legacyheader bits 621, first padding bits 622, and parity bits 623 disposed inthis order.

The legacy header bits 621 have a length of 5 octets and represent theLDPC codeword of the legacy header 602 illustrated in FIG. 6. The firstpadding bits 622 have a length of 6 octets and represent the LDPCcodeword of the first padding field 603 illustrated in FIG. 6. Theparity bits 623 have a length of 21 octets and represent parity bitsused for error correction coding performed on the legacy header bits 621and the first padding bits 622.

In addition, as illustrated in FIG. 10, the NG60 header LDPC codeword630 includes NG60 header bits 631, second padding bits 632, and paritybits 633 in this order.

The NG60 header bits 631 have a length of 5 octets and represent theLDPC codeword of the NG60 header 604 illustrated in FIG. 6. The secondpadding bits 632 have a length of 6 octets and represent the LDPCcodeword of the second padding field 605 illustrated in FIG. 6. Theparity bits 633 have a length of 21 octets and represent parity bitsused for error correction coding of the NG60 header bits 631 and thesecond padding bits 632.

The modulator 313 illustrated in FIG. 8 modulates the plurality of LDPCcodewords (the legacy header LDPC codeword, the NG60 header LDPCcodeword, the data LDPC codeword) included in the MF control PHY PPDU600 output from the LDPC encoder 312 by using DBPSK and converts theplurality of LDPC codewords into a stream of complex constellationpoints.

Note that the modulator 313 performs DBPSK modulation on the NG60 headerLDPC codeword with a phase rotation of, for example, 90 degrees. Thatis, the modulator 313 sets the phase of the modulation signal of theNG60 header LDPC codeword to a phase rotated by 90 degrees with respectto the phase of the modulation signal of the other portion. The amountof rotation of the phase is not limited to 90 degrees. For example, theamount of rotation may be −90 degrees. Any other amount of rotation maybe employed if the receiving device can distinguish the constellationpoint of the modulation signal of the portion of the NG60 header 604from the constellation point of the modulation signal of the otherportion.

The modulator 313 includes a first modulation unit 316 and a secondmodulation unit 317.

The first modulation unit 316 performs DBPSK modulation similar to thatof legacy WiGig on the plurality of LDPC codewords other than the NG60header LDPC codeword, that is, the legacy header LDPC codeword and thedata LDPC codeword.

The second modulation unit 317 performs DBPSK modulation on the NG60header LDPC codeword by using a phase obtained by rotating the phaseused in the DBPSK modulation of the first modulation unit 316 by, forexample, 90 degrees. The amount of rotation of the phase is not limitedto 90 degrees. For example, the amount of rotation may be −90 degrees.Any other amount of rotation may be employed if the receiving device candistinguish the constellation point of the modulation signal of theportion of the NG60 header 604 from the constellation point of themodulation signal of the other portion.

Note that the modulator 313 selectively uses the first modulation unit316 and the second modulation unit 317 for each of the plurality of LDPCcodewords on the basis of, for example, a control signal generated bythe controller 200.

In this way, with the phase of the portion of the NG60 header 604rotated, the modulator 313 outputs, to the spreader 314, the MF controlPHY PPDU 600 having the modulated portion from the legacy header 602 tothe second padding field 605 and the modulated portion of the data field608. Note that in the MF control PHY PPDU 600, the phase of the portionof the NG60 header 604 is rotated.

The spreader 314 spreads the constellation points of the stream includedin the MF control PHY PPDU 600 output from the modulator 313 by usingthe Golay sequence Ga32. Thereafter, the spreader 314 outputs, to theSTC encoder 315, the MF control PHY PPDU 600 having the spread portionfrom the legacy header 602 to the second padding field 605 and thespread portion of the data field 608.

The STC encoder 315 performs a well-known space-time coding processusing, for example, the Alamouti code on the spread constellation pointscorresponding to the data LDPC codeword to generate a plurality ofspace-time streams from the data field 608. Thereafter, the STC encoder315 transmits, to the transmission RF front end 320, the MF control PHYPPDU 600 having the portion from the legacy header 602 to the secondpadding field 605 that is spread and the portion of the data field 608that is spread and is subjected to a space-time streaming process.

The transmission RF front end 320 converts the MF control PHY PPDU 600output from the transmission baseband processor 310 illustrated in FIG.5 into a radio signal in the 60-GHz band by using a plurality of radioantennas provided in the antenna unit 400 and outputs the radio signal.At this time, the transmission RF front end 320 transmits the pluralityof space-time streams generated from the data field 608 in parallel andseparately. In addition, as described above, in the MF control PHY PPDU600, the phase of the portion of the NG60 header 604 is rotated.

Note that when the legacy WiGig device receives such an MF control PHYPPDU 600, the portion from the first padding field 603 to the data field608 (refer to FIG. 6) is processed as a portion of the data field 13 ofthe LF control PHY PPDU 10 (refer to FIG. 1).

Configuration of Reception Processor

The reception processor 500 performs predetermined reception basebandprocessing on the received signal output from the antenna unit 400 andoutputs the signal to the controller 200. The reception processor 500includes a reception RF front end 510 and a reception baseband processor520.

The reception RF front end 510 receives a radio signal transmitted fromanother wireless communication device using a plurality of radioantennas provided in the antenna unit 400 and outputs the receivedsignal to the reception baseband processor 520.

Note that the received signal may include the MF control PHY PPDU 600transmitted from the NG60 WiGig device (a device having the sameconfiguration as the wireless communication device 100). As describedabove, the MF control PHY PPDU 600 has the portion from the legacyheader 602 to the second padding field 605 illustrated in FIG. 6 and theportion of the data field 608 that are modulated with the phase of theportion of the NG60 header 604 rotated.

If the received signal is an MF control PHY PPDU 600, the receptionbaseband processor 520 performs reception baseband processing, such asspace-time decoding, despreading, DBPSK demodulation, LDPC decoding, anddescrambling, on the received signal. Thereafter, the reception basebandprocessor 520 outputs, to the controller 200, the MF control PHY PPDU600 subjected to the reception baseband processing.

Configuration of Reception Baseband Processor

FIG. 11 is a block diagram illustrating an example of the configurationof the reception baseband processor 520.

As illustrated in FIG. 11, the reception baseband processor 520 includesa channel estimator 521, an STC decoder 522, a despreader 523, ademodulator 524, an LDPC decoder 525, and a descrambler 526.

The reception baseband processor 520 first decodes the portionscorresponding to the NG60 header 604 and the legacy header 602 of thereceived signal and acquires the original NG60 header 604 and the legacyheader 602. Thereafter, the reception baseband processor 520 decodes theportion corresponding to the data field 608 of the received signal onthe basis of information in the acquired NG60 header 604 and the legacyheader 602.

Hereinafter, the stage of decoding the portions corresponding to theNG60 header 604 and the legacy header 602 is referred to as a “headerdecoding stage”. In addition, the stage of decoding the portioncorresponding to the data field 608 after the header decoding stage isreferred to as a “data decoding stage”.

The function of each of the units of the reception baseband processor520 in the header decoding stage is described first.

If the received signal output from the reception RF front end 510includes the MF control PHY PPDU 600, the channel estimator 521 performschannel estimation on the basis of the information in the NG60 CEFs 607(refer to FIG. 6) of the received signal. Thereafter, the channelestimator 521 outputs the result of channel estimation to the STCdecoder 522 and the demodulator 524.

The STC decoder 522 outputs, to the despreader 523, the received signaloutput from the reception RF front end 510 and holds the same signal forprocessing to be performed in the data decoding stage.

The despreader 523 performs despreading on the portion corresponding tothe legacy header 602 to the second padding field 605 in the receivedsignal output from the STC decoder 522. Note that such despreading is anarithmetic process that is the reverse of the spreading performed by thespreader 314 of the transmission baseband processor 310. Thereafter, thedespreader 523 outputs, to the demodulator 524, the received signalhaving the despread portion corresponding to the legacy header 602 tothe second padding field 605.

The demodulator 524 demodulates the despread portion of the receivedsignal output from the despreader 523 on the basis of the result ofchannel estimation performed by the channel estimator 521 (the result ofestimation using CEF 17 (refer to FIG. 1)). Note that such demodulationis an arithmetic operation that is the reverse of the modulationperformed by the modulator 313 of the transmission baseband processor310. That is, the demodulator 524 performs DBPSK demodulation on theportion corresponding to the NG60 header LDPC codeword by using a phaseobtained by rotating the phase used for DBPSK demodulation performed onthe other portion by, for example, 90 degrees.

The demodulator 524 includes a first demodulation unit 527 and a seconddemodulation unit 528.

The first demodulation unit 527 performs an arithmetic operation that isthe reverse of the DBPSK modulation performed by the first modulationunit 316 on the portion corresponding to the legacy header 602 and thefirst padding field 603 in the received signal output from thedespreader 523. In this manner, the first demodulation unit 527demodulates the portion of the received signal.

The second demodulation unit 528 performs an arithmetic operation thatis the reverse of the DBPSK modulation performed by the secondmodulation unit 317 on the portions of the received signal output fromthe despreader 523 which correspond to the NG60 header 604 and thesecond padding field 605. In this manner, the second demodulation unit528 demodulates the portions.

Note that the demodulator 524 selectively uses the first demodulationunit 527 and the second demodulation unit 528 for the received signaloutput from the despreader 523 on the basis of, for example, a controlsignal generated by the controller 200.

The signal output from the first demodulation unit 527 corresponds tothe legacy header 602, the first padding field 603, and the secondpadding field 605. In addition, the signal output from the seconddemodulation unit 528 corresponds to the NG60 header 604. Accordingly,the demodulator 524 can identify the portion corresponding to the NG60header 604 in the received signal and extract the portion. Thedemodulator 524 outputs, to the LDPC decoder 525, the reception signalhaving the demodulated portion from the legacy header 602 to the secondpadding field 605 with the portion corresponding to the NG60 header 604being indicated.

The LDPC decoder 525 performs LDPC decoding on the demodulated portionof the received signal output from the demodulator 524. Note that suchdecoding is the reverse of the LDPC coding performed by the LDPC encoder312 of the transmission baseband processor 310 illustrated in FIG. 8.Thereafter, the LDPC decoder 525 outputs, to the descrambler 526, thereceived signal having LDPC-decoded portion corresponding to the legacyheader 602 to the second padding field 605.

The descrambler 526 descrambles the LDPC-decoded portion of the receivedsignal output from the LDPC decoder 525. Noted that such descrambling isan arithmetic operation that is the reverse of the scrambling performedby the scrambler 311 of the transmission baseband processor 310illustrated in FIG. 8. Thereafter, the descrambler 526 outputs, to theSTC decoder 522, the bits of the original NG60 header 604 obtainedthrough the descrambling. In this manner, the header decoding stage iscompleted.

Note that as described above, the details of the MF control PHY PPDU 600can be acquired from the legacy header 602 and the NG60 header 604.

The function of each of the units of the reception baseband processor520 in the data decoding stage is described below.

The STC decoder 522 performs space-time decoding on a portion of thereceived signal corresponding to the data field 608 on the basis of thebits of the NG60 header 604 output from the descrambler 526 and theresult of channel estimation performed by the channel estimator 521 (theresult of estimation using the NG60 CEFs 607 (refer to FIG. 6)). Notethat such space-time decoding is an arithmetic operation that is thereverse of the space-time coding performed by the STC encoder 315 of thetransmission baseband processor 310 illustrated in FIG. 8. Thereafter,the STC decoder 522 outputs the result of the space-time decoding to thedespreader 523.

The despreader 523, the first demodulation unit 527 of the demodulator524, the LDPC decoder 525, and the descrambler 526 perform processingthat is the same as the processing performed on the legacy header 602and the like in the header decoding stage.

In this manner, the descrambler 526 acquires the bits of the originaldata field 608 and outputs the acquired bits of the data field 608 tothe controller 200 together with the information about the legacy header602 and the NG60 header 604. Such bits of the data field 608 areanalyzed and processed by the controller 200 illustrated in FIG. 5.

Effect of Present Embodiment

As described above, the wireless communication device 100 according tothe present embodiment can generate and transmit an MF control PHY PPDU600. The MF control PHY PPDU 600 is a control PHY PPDU having a portioncorresponding to the data field of a control PHY PPDU of the legacyWiGig, where the portion has data to be transmitted by using a variablebandwidth and the NG60 header 604 having information about transmissionby using the variable bandwidth set forth therein. In addition, the MFcontrol PHY PPDU 600 is a control PHY PPDU modulated by rotating thephase of a portion corresponding to the NG60 header 604 by, for example,90 degrees with respect to the phase of the other portion.

In addition, upon receiving the MF control PHY PPDU 600, the wirelesscommunication device 100 according to the present embodiment canidentify the NG60 header 604 on the basis of the above-describedrotation of the phase and decode the data transmitted using the variablebandwidth. That is, the wireless communication device 100 can determinewhether the received signal is an LF control PHY PPDU 10 or an MFcontrol PHY PPDU 600 on the basis of the identification informationgiven to the NG60 header 604.

Accordingly, the wireless communication device 100 according to thepresent embodiment can support transmission that makes use of variablebandwidth while maintaining backward compatibility with legacy WiGig.That is, the NG60 WiGig technology can increase the robustness of datatransmission and increase the data transmission rate. In addition, thewireless communication device 100 according to the present embodimentcan transmit and receive the MF control PHY PPDU 700 distinctively fromthe LF control PHY PPDU 10.

Note that upon receiving the LF control PHY PPDU 10, the wirelesscommunication device 100 directly outputs the portion of the data field13 (FIG. 1) of the LF control PHY PPDU 10 to the controller 200. Thatis, in the header decoding stage, the wireless communication device 100demodulates the legacy header 602. In addition, in the data decodingstage, the wireless communication device 100 performs despreading, DBPSKdemodulation, LDPC decoding, and descrambling on the portioncorresponding to the data field 13 without performing space-timedecoding.

Alternatively, the wireless communication device 100 may include both areception processor for performing processing based on the LF controlPHY PPDU and a reception processor for performing processing based onthe MF control PHY PPDU. Thereafter, if a control PHY PPDU is includedin the received signal, the wireless communication device 100 mayprocess the received signal by using both the reception processors inparallel until the format is identified.

Another Example of Transmission Method

Note that when a channel having a channel bandwidth larger than thestandard bandwidth is available, the wireless communication device 100may transmit the MF control PHY PPDU 600 by using such a channel.

For example, the transmission baseband processor 310 makes (M−1) copies(M is a natural number greater than 1) of the portion from the legacypreamble 601 to the second padding field 605 in a channel having achannel bandwidth that is M times the standard bandwidth. Thereafter,the transmission baseband processor 310 applies an appropriate frequencyoffset to each of the copies, multiplexes the original data and the(M−1) copies in the frequency direction on the above-mentioned channel,and transmits the original data and the (M−1) copies at the same time.

FIG. 12 is a diagram illustrating an example of transmission of the MFcontrol PHY PPDU 600 (refer to FIG. 6) on a channel having a channelbandwidth that is twice the standard bandwidth. FIG. 12 corresponds toFIG. 6.

As illustrated in FIG. 12, it is assumed that a channel bandwidth 641 istwice a standard bandwidth 642. In this case, the transmission basebandprocessor 310 sets the frequency offset of the portion from a legacypreamble 601 ₁ to a second padding field 605 ₁ (the original data) to,for example, 50% of the standard bandwidth. In addition, thetransmission baseband processor 310 sets the frequency offset of theportion from a legacy preamble 601 ₂ to a second padding field 605 ₂(copied data) to −50% of the standard bandwidth.

In this manner, by effectively using the channel bandwidth, the NG60WiGig technology can further enhance the robustness of datatransmission. Note that upon receiving a plurality of sets of portionsfrom the legacy preamble 601 to the second padding field 605, thereception baseband processor 520 of the wireless communication device100 on the receiving side may integrate these sets of data.

Second Embodiment

The NG60 WiGig device used when identification information is providedin the NG60 header by setting the format identification information inthe control PHY PPDU is described below as the second embodiment of thepresent disclosure.

Configuration of Device

FIG. 13 is a block diagram illustrating an example of the configurationof a wireless communication device (an NG60 WiGig device) according tothe present embodiment. FIG. 13 corresponds to FIG. 5 according to thefirst embodiment. The same elements as those in FIG. 5 are designated bythe same reference numerals, and descriptions of the elements are notrepeated.

Although not illustrated, the wireless communication device according tothe present embodiment includes, for example, a CPU, a storage medium,such as a ROM, storing a control program, a work memory, such as a RAM,and a communication circuit. In this case, the function of each of theelements of the wireless communication device is provided by, forexample, the CPU executing the control program.

As illustrated in FIG. 13, a wireless communication device 100 a has acontroller 200 a, a transmission processor 300 a, an antenna unit 400,and a reception processor 500 a.

The controller 200 a includes a PPDU generator 210 a instead of the PPDUgenerator 210 according to the first embodiment. The transmissionprocessor 300 a includes a transmission baseband processor 310 a insteadof the transmission baseband processor 310 according to the firstembodiment. The reception processor 500 a has a reception basebandprocessor 520 a instead of the reception baseband processor 520according to the first embodiment.

The PPDU generator 210 a generates an MF control PHY PPDU from thepayload data of the PSDU and transmits the generated MF control PHY PPDUby using the transmission processor 300 and the antenna unit 400. Notethat the PPDU generator 210 a generates an MF control PHY PPDU having aformat that differs from that of the first embodiment.

Control PHY PPDU Format

FIG. 14 is a diagram illustrating an example of the format of the MFcontrol PHY PPDU according to the present embodiment. FIG. 14corresponds to FIG. 1 and FIG. 6 of the first embodiment.

As illustrated in FIG. 14, the MF control PHY PPDU 700 of the presentembodiment includes a legacy preamble 701, a legacy header 702, an NG60header 703, an NG60 STF 704, a plurality of NG60 CEFs 705, and a datafield 706 in this order.

Note that when used for beam refinement, the MF control PHY PPDU 700 mayfurther include an AGC subfield 707 and a TRN-R/T subfield 708 after thedata field 706. That is, the AGC subfield 707 and the TRN-R/T subfield708 are optional.

The MF control PHY PPDU 700 according to the present embodiment does notinclude the first padding field 603 and the second padding field 605(refer to FIG. 6) that are provided in the MF control PHY PPDU 600according to the first embodiment.

The legacy preamble 701 has the same waveform as the legacy preamble 11in the LF control PHY PPDU 10.

The legacy header 702 has the same configuration as the legacy header 12of the LF control PHY PPDU 10 (refer to FIG. 2).

The NG60 header 703 provides information about the details of the MFcontrol PHY PPDU 700 by itself or together with the legacy header 702.The details of the structure of the NG60 header 703 are described below.

The NG60 STF 704 is an area used for retraining of automatic gaincontrol (AGC). That is, the NG60 STF 704 has the same waveform as theNG60 STF 606 (refer to FIG. 6) in the MF control PHY PPDU 600 accordingto the first embodiment.

The plurality of NG60 CEFs 705 are an area used for channel estimationof a plurality of space-time streams generated from the data field 706.That is, the plurality of NG60 CEFs 705 have the same waveform as theplurality of NG60 CEFs 607 (refer to FIG. 6) in the MF control PHY PPDU600 according to the first embodiment.

The data field 706 stores the payload data of the PSDU. That is, thedata field 706 corresponds to the data field 608 (refer to FIG. 6) inthe MF control PHY PPDU 600 according to the first embodiment.

The AGC subfield 707 and the TRN-R/T subfield 708 has information aboutbeam refinement set forth therein. That is, the AGC subfield 707 and theTRN-R/T subfield 708 have waveforms similar to those of the AGC subfield609 and the TRN-R/T subfield 610 (refer to FIG. 6) in the MF control PHYPPDU 600 according to the first embodiment, respectively.

That is, the PPDU generator 210 a generates the MF control PHY PPDU 700having a structure generated by removing the first padding field 603 andthe second padding field 605 from the MF control PHY PPDU 600 accordingto the first embodiment.

Note that unlike the NG60 header 604 according to the first embodiment,the NG60 header 703 of the MF control PHY PPDU 700 has formatidentification information indicating that it is a portion of the NG60header 703 set forth therein. The format identification information is apredetermined sequence.

FIG. 15 is a diagram illustrating an example of the structure of theNG60 header 703. FIG. 15 corresponds to FIG. 7 according to the firstembodiment. FIG. 16 is a diagram illustrating another example of thestructure of the NG60 header 703. For the NG60 header 703, either one ofthe structure illustrated in FIG. 15 and the configuration illustratedin FIG. 16 can be adopted.

As illustrated in FIG. 15, the NG60 header 703 has a structure similarto that of the NG60 header 604 (refer to FIG. 7) according to the firstembodiment, except that a format identification field is provided priorto a CBW field. In addition, as illustrated in FIG. 16, the NG60 header703 has a structure similar to that of the NG60 header 604 according tothe first embodiment, except that the NG60 header 703 includes a formatidentification/CBW field instead of the CBW field. Descriptions of thesame fields are not repeated.

The format identification field illustrated in FIG. 15 has 8-bitinformation predetermined set forth therein as identificationinformation indicating the start position of the NG60 header 703. Thatis, in the case of the structure illustrated in FIG. 15, formatidentification information and channel bandwidth information areseparately signaled.

The format identification/CBW field illustrated in FIG. 16 has 8-bitinformation set forth therein which serves as identification informationindicating the start position of the NG60 header 703 and informationspecifying the channel bandwidth (CBW) at the same time. That is, in thecase of the structure illustrated in FIG. 16, the format identificationinformation and the channel bandwidth information are signaled together.

The information set forth in the CBW field or the formatidentification/CBW field can be one of a plurality of predefinedsequences, such as Golay sequences Ga8 each having a length of 8.

By using such a structure, the NG60 header 703 of the MF control PHYPPDU 700 can be identified on the receiving side by detecting theidentification information. Thus, the need for the phase rotation at thetime of modulation as in the first embodiment is eliminated.

Note that the PPDU generator 210 a sets the value of the length field ofthe legacy header 602 while taking into account the entire portion fromthe NG60 header 703 to the data field 706. As a result, upon receivingthe MF control PHY PPDU 700, the legacy WiGig device can correctlydetermine the number of data octets of the PSDU.

As used herein, as described in the first embodiment, the value of thelength field of the legacy header 702 is referred to as a legacy lengthfield value L_(LH), and the value of the length field of the NG60 header703 is referred to as a NG60 length field value L_(NH).

According to the calculation method described in the first embodiment,the equivalent length of the NG60 STF 704 and NG60 CEFs 705 is6.25+N_(sts)×2.25 octets. Therefore, the legacy length field valueL_(LH) is the sum of the NG60 length field value L_(NH), the length ofthe NG60 header 703 (i.e., 6 octets), and the equivalent length of theNG60 STF 704 and NG60 CEFs 705. That is, the legacy length field valueL_(LH) is given by, for example, the following expression (9):

L _(LH) =L _(NH)+12.25+N _(sts)×2.25   (9)

Therefore, according to the logic described in the first embodiment, thefollowing expression (10) is derived:

N _(sts)×72≦1010.75−L _(NH)   (10)

The PPDU generator 210 a generates an MF control PHY PPDU 600 such thatthe legacy length field value L_(LH) and the NG60 length field valueL_(NH) satisfy expressions (9) and (10).

Note that like the MF control PHY PPDU 600 of the first embodiment, inthe case of the MF control PHY PPDU 700, the portion from the legacypreamble 701 to the NG60 header 703 needs to be transmitted using astandard bandwidth.

Configuration of Transmission Baseband Processor

The transmission baseband processor 310 a has the same configuration asthe transmission baseband processor 310 (refer to FIG. 8) according tothe first embodiment except for the portion of the modulator 313.

Note that the above-described scrambling process performed by thetransmission baseband processor 310 a is applied to the portion of thelength field of the legacy header 702 in the MF control PHY PPDU 700 andthe subsequent portion and the portion from the length field of the NG60header 703 to the data field 706. In addition, the above-describedprocesses such as encoding, modulation, and spreading performed by thetransmission baseband processor 310 a is applied to the portions of thelegacy header 702, the NG60 header 703, and the data field 706 in the MFcontrol PHY PPDU 700.

Therefore, for example, the LDPC encoder 312 outputs an LDPC codewordincluding the bits of the legacy header 702 and the NG60 header 703(hereinafter referred to as a “header LDPC codeword”) and a data LDPCcodeword not including the bits of the legacy header 702 and the NG60header 703.

Note that as described above, the transmission baseband processor 310 adoes not perform a scrambling process on the area of the formatidentification field or the format identification/CBW field of the NG60header 703, which has the identification information of the NG60 header703 (hereinafter referred to as “identification information descriptionarea”) set forth therein. The transmission baseband processor 310 astops performing a scrambling process on the above-described area on thebasis of, for example, a control signal that is generated by thecontroller 200 a and that indicates the position of the identificationinformation description area.

FIG. 17 is a diagram illustrating an example of the structure of theheader LDPC codeword. FIG. 17 corresponds to FIG. 4 and FIG. 9 of thefirst embodiment.

As illustrated in FIG. 17, the header LDPC codeword 720 has a legacyheader bits 721, NG60 header bits 722, and parity bits 723 disposed inthis order.

The legacy header bits 721 have a length of 5 octets and represent theLDPC codeword of the legacy header 702. The NG60 header bits 722 have alength of 6 octets and represent the LDPC codeword of the NG60 header703. The parity bits 723 have a length of 21 octets and represent paritybits used for error correction coding of the legacy header bits 721 andthe NG60 header bits 722.

The modulator according to the present embodiment (not illustrated) hasthe same configuration as the modulator 313 according to the firstembodiment, except that the modulator does not include the secondmodulation unit 317.

The NG60 header 703 can be identified by the presence of theidentification information description area in the NG60 header 703.Therefore, unlike the first embodiment, the modulator according to thepresent embodiment does not apply phase rotation of DBPSK modulation tothe portion of the NG60 header 703.

That is, the modulator according to the present embodiment modulates allof the header LDPC codeword 720 (refer to FIG. 17) and the data LDPCcodeword output from the LDPC encoder 312 by using the same DBPSK andconverts the codewords into a stream of complex constellation points. Inother words, the modulator according to the present embodiment performsthe same DBPSK modulation on the portion of the NG60 header 703 and theportion other than the NG60 header 703 which includes the legacy header702.

Configuration of Reception Baseband Processor

The reception baseband processor 520 a illustrated in FIG. 13 has thesame configuration as the reception baseband processor 520 (refer toFIG. 11) according to the first embodiment except for the portion of thedemodulator 524.

Note that the above-described descrambling process performed by thereception baseband processor 520 a is applied to a portion of the MFcontrol PHY PPDU 700 after the length field of the legacy header 702 anda portion from the length of the NG60 header 703 Field to the data field706. In addition, the above-described processing such as decoding,demodulation, and despreading performed by the reception basebandprocessor 520 a is applied to the portions of the legacy header 702, theNG60 header 703, and the data field 706 of the MF control PHY PPDU 700.

The demodulator according to the present embodiment (not illustrated)has the same configuration as the demodulator 524 of the firstembodiment except that the demodulator does not include the seconddemodulation unit 528.

The NG60 header 703 can be identified on the receiving side on the basisof the presence of the identification information description area ofthe NG60 header 703 instead of the phase rotation at the time ofmodulation of the NG60 header 703. Therefore, unlike the firstembodiment, the demodulator according to the present embodiment does notperform phase rotation of the DBPSK demodulation for the NG60 header 703in the header decoding stage.

Subsequently, in the header decoding stage, the descrambler 526 detectsthe identification information set forth in the identificationinformation description area and outputs the bits of the NG60 header 703to the STC decoder 522 on the basis of the detected identificationinformation. The descrambler 526 detects the identification informationdescription area on the basis of, for example, a control signal that isgenerated by the controller 200 a and that indicates the position of theidentification information description area. Alternatively, thedescrambler 526 may detect the identification information descriptionarea on the basis of the position of the STF 16 (refer to FIG. 1).

Subsequently, like the first embodiment, the reception processor 500 aperforms the processing of the data decoding stage.

Effect of Present Embodiment

As described above, the wireless communication device 100 a according tothe present embodiment is capable of generating the MF control PHY PPDU700 having the identification information for identifying the NG60header 703 in the data field of the control PHY PPDU of the legacy WiGigand transmitting the generated MF control PHY PPDU 700.

In addition, upon receiving the MF control PHY PPDU 700, the wirelesscommunication device 100 a according to the present embodiment iscapable of identifying the NG60 header 703 on the basis of thedescription of the identification information and decoding the data thatis a target of transmission that makes use of variable bandwidth.

Accordingly, by adopting the wireless communication device 100 aaccording to the present embodiment can support transmission usingvariable bandwidth without performing phase rotation in modulation anddemodulation, while maintaining backward compatibility with legacyWiGig.

In addition, the wireless communication device 100 a according to thepresent embodiment is capable of detecting the NG60 header 703 whenprocessing the first LDPC codeword (i.e., the header LDPC codeword 720),since the header LDPC codeword 720 includes the bits of the legacyheader 702 and the NG60 header 703. In contrast, according to the firstembodiment, it is difficult to detect the NG60 header 604 unless thesecond LDPC codeword (i.e., the NG60 header LDPC codeword 630) isprocessed.

Therefore, as compared with the first embodiment, the wirelesscommunication device 100 a according to the present embodiment iscapable of identifying the MF control PHY PPDU earlier from the receivedsignal. Thus, power consumption can be reduced.

In addition, the MF control PHY PPDU 700 of the wireless communicationdevice 100 a according to the present embodiment does not have the firstpadding field 603 and the second padding field 605 that are present inthe MF control PHY PPDU 600 according to the first embodiment.Therefore, the wireless communication device 100 a according to thepresent embodiment can remove the cause of excessive overhead andimprove the data transmission efficiency, as compared with the firstembodiment.

Note that upon receiving the LF control PHY PPDU 10, the wirelesscommunication device 100 a directly outputs the portion (FIG. 1) of thedata field 13 of the LF control PHY PPDU 10 to the controller 200.Alternatively, as described in the first embodiment, the wirelesscommunication device 100 a may include both a reception processor forthe LF control PHY PPDU and a reception processor for the MF control PHYPPDU and process the received signal by using both the receptionprocessors in parallel until the format is identified.

Another Example of Transmission Method

In addition, according to the present embodiment, the MF control PHYPPDU 700 may be transmitted by using a channel having a channelbandwidth larger than the standard bandwidth.

FIG. 18 illustrates an example of transmission of the MF control PHYPPDU 700 (refer to FIG. 14) through a channel having a channel bandwidththat is twice the standard bandwidth. FIG. 18 corresponds to FIG. 14 andFIG. 12 of the first embodiment.

As illustrated in FIG. 18, it is assumed that a channel bandwidth 741 istwice a standard bandwidth 742. In this case, for example, thetransmission baseband processor 310 a sets the frequency offset of theportion from a legacy preamble 701 ₁ to an NG60 header 703 ₁ (originaldata) to 50% of the standard bandwidth. Thereafter, the transmissionbaseband processor 310 sets the frequency offset of the portion from alegacy preamble 701 ₂ to an NG60 header 703 ₂ (copied data) to −50% ofthe standard bandwidth.

Another Example of Position of Identification Information

In addition, the position of the identification information descriptionarea and the description format of the identification information arenot limited to the above-described examples. For example, the wirelesscommunication device 100 a on the transmitting side may describe theidentification information using a header check sequence (HCS) checking.In this case, if the HCS checking of the NG60 header 703 is successful,the wireless communication device 100 a on the receiving side determinesthat the MF control PHY PPDU has been received. However, if the HCSchecking is not successful, the wireless communication device 100 a onthe receiving side determines that the LF control PHY PPDU has beenreceived.

Modifications of Embodiments

While the above-described embodiments have been described with referenceto the example in which the configuration of the transmission systemcorresponding to NG60 WiGig and the configuration of the receptionsystem corresponding to NG60 WiGig are disposed in one device, theconfiguration is not limited thereto. That is, the configuration of thetransmission system corresponding to the NG60 WiGig and theconfiguration of the reception system corresponding to the NG60 WiGigmay be disposed in different wireless communication devices.

<Overview of Present Disclosure>

According to the present disclosure, a wireless communication deviceincludes a physical layer protocol data unit (PPDU) generator thatgenerates a PPDU including a legacy preamble, a legacy header, anon-legacy header, a data field, and identification informationindicating that the non-legacy header is included in the PPDU and atransmission unit that transmits the PPDU.

Note that in the wireless communication device, the identificationinformation may be format identification information included in a topportion of the non-legacy header.

In addition, in the wireless communication device, the non-legacy headermay be disposed immediately after the legacy header in the physicallayer protocol data unit.

In addition, in the wireless communication device, the non-legacy headermay further include information regarding one or more channelbandwidths, and the format identification information and theinformation regarding the one or more channel bandwidths may beindividually described in the non-legacy header.

In addition, in the wireless communication device, the non-legacy headermay further include information regarding one or more channelbandwidths, and the format identification information and theinformation regarding the one or more channel bandwidth may be jointlydescribed in a single field in the non-legacy header.

In addition, in the wireless communication device, each of the formatidentification information and the information regarding the one or morechannel bandwidths may be described in the non-legacy header by using asequence, and the sequence may be selected from among a plurality ofsequences defined in accordance with the channel bandwidths.

In addition, in the wireless communication device, the transmitter mayinclude an encoder that performs error correction coding on the PPDU byencoding the legacy header and the non-legacy header into a singlecodeword, and the modulator may map the encoded legacy header and theencoded non-legacy header to the same constellation.

In addition, in the wireless communication device, the transmitter mayinclude a scrambler that performs scrambling on the PPDU and an encoderthat performs error correction coding on the scrambled PPDU. Thescrambling may not be performed on the identification information.

In addition, in the wireless communication device, the transmitter mayinclude a modulator that modulates the PPDU, and the modulator maymodulate the non-legacy header by using a first phase that differs froma second phase used to modulate one of the legacy preamble and thelegacy header.

A wireless communication method according to the present disclosureincludes generating a physical layer protocol data unit (PPDU) includinga legacy preamble, a legacy header, a non-legacy header, a data field,and identification information indicating that the non-legacy header isincluded in the PPDU and transmitting the DU.

The present disclosure is useful as a wireless communication device anda wireless communication method capable of increasing the datatransmission rate in WiGig technology.

What is claimed is:
 1. A wireless communication device comprising: aphysical layer protocol data unit (PPDU) generator, which in operation,generates a PPDU including a legacy preamble, a legacy header, anon-legacy header, a data field, and identification informationindicating that the non-legacy header is included in the PPDU; and atransmitter, which in operation, transmits the PPDU.
 2. The wirelesscommunication device according to claim 1, wherein the identificationinformation is format identification information included in a topportion of the non-legacy header.
 3. The wireless communication deviceaccording to claim 1, wherein the non-legacy header is disposedimmediately after the legacy header in the PPDU.
 4. The wirelesscommunication device according to claim 2, wherein the non-legacy headerincludes information regarding one or more channel bandwidths, andwherein the format identification information and the informationregarding the one or more channel bandwidths are individually describedin the non-legacy header.
 5. The wireless communication device accordingto claim 2, wherein the non-legacy header includes information regardingone or more channel bandwidths, and wherein the format identificationinformation and the information regarding the one or more channelbandwidths are jointly described in a single field in the non-legacyheader.
 6. The wireless communication device according to claim 5,wherein each of the format identification information and theinformation regarding the one or more channel bandwidths is described inthe non-legacy header by using a sequence, and the sequence is selectedfrom among a plurality of sequences defined in accordance with thechannel bandwidths.
 7. The wireless communication device according toclaim 1, wherein the transmitter includes: an encoder, which inoperation, performs error correction coding on the PPDU by encoding thelegacy header and the non-legacy header into a single codeword; and amodulator, which in operation, maps the encoded legacy header and theencoded non-legacy header to the same constellation.
 8. The wirelesscommunication device according to claim 1, wherein the transmitterincludes a scrambler, which in operation, performs scrambling on thePPDU and an encoder, which in operation, performs error correctioncoding on the scrambled PPDU, and wherein the scrambling is notperformed on the identification information.
 9. The wirelesscommunication device according to claim 1, wherein the transmitterincludes a modulator, which in operation, modulates the PPDU, andwherein the modulator modulates the non-legacy header by using a firstphase that differs from a second phase used to modulate one of thelegacy preamble and the legacy header.
 10. A wireless communicationmethod comprising: generating a physical layer protocol data unit (PPDU)including a legacy preamble, a legacy header, a non-legacy header, adata field, and identification information indicating that thenon-legacy header is included in the PPDU; and transmitting the PPDU.